Mechanical unloader for stokers



Oct. 23, 1934.

H. C. CARTER MECHANICAL UNLOADER FOR STOKERS Filed Feb. 23, 1932 2Sheets-Sheet l NWAEA/TU H c CARTER 7 7- TERA/E K Oct. 23, 1934.

1 H. c. CARTER 1 1,978,011

MECHANICAL UNLOADER FOR STOKERS Fi led Feb. 25, 1952 2 Sheets-Sheet 2 4TTURNEW mechanism illustrated Patented Oct. 23, 1934 MECHANICAL UNLOADERFOR STOKERS Haskell 0. Carter, Portland, 0reg., assignor to Iron FiremanManufacturing Company, Port-.

land, Oreg.

Application February 23, 1932, Serial No. 594,411

3 Claims.

This invention relates generally to underfeed stokers, and particularlyto a mechanical unloader therefor.

The main object of this invention is to provide a simple and eflicientmeans for moving an overload from the driving mechanism of the stoker,with particular reference to the type of driving in Patent Number1,779,824, dated October 28, 1930, to C. J. Parker.

The second object is to construct an unloading device which cannot beeasily tampered with or rendered inoperative, and which will includemeans forgiving notice, either audibly or visibly, that the device hasfunctioned and, if desired, stop the operation of the stoker motor.

These, and other objects, will become more apparent from thespecification following as illustrated in the accompanying drawings, in

which:

Fig. 1 is a front elevation of a stoker gear case with parts of themechanism broken away in.

section.

Fig. 2 is an elevation of the gear case with the front cover removed andshowing certain parts cut away in section.

Fig. 3 is a side elevation of a gear case and fuel magazine with partsbroken away along the line 3--3 in Fig. 1.

' Fig. 4 is a section taken along in Fig. 1.

Fig. 5 is a fragmentar view showing a modified form of the deviceincluding the signal and motor control.

Fig. 5 is a fragmentary view showing a modification with parts brokenaway in section.

Fig. '7 is a fragmentary section taken along the line '7-'7 in Fig. 6.

Fig. 8 is a section taken along the line 8-8 in Fig. '7.

Similar numbers of reference refer to similar parts throughout theseveral views.

Referring in detail to the drawings, there is shown a portion of ahopper 10 of an underfeed coal stoker and also a worm 11 by means ofwhich fuel is conveyed from the hopper to the combustion zone. To thehopper 10 is attached a gear case 12 to which power is delivered by amotor (not shown) through a shaft 13 and, as described in theabove-mentioned patent, to a shaft 14 on which is mounted a gear 15whose hub 16 is secured on the shaft 14 by the heavy shear pin 17.

The gear 15 meshes with any one of the three pinions 18, 19 or 20 whoserespective shafts 21 the I line '44-.

are carried in a rotatable cage 22. Attached t0 second the pinion 18 isa gear 23. Attached to the. pinion 19 is a gear 24. Attached to thepinion 20 or integral therewith is a gear 25 equal in diameter to thepinion 20. The gears 23, 24 and 25 mesh at all times with the pinion 26which is directly connected to'the worm 11.

The cage 22 is provided-with a plurality of notches 2'7 and 28alternating about-the periphery .thereof and adapted to receive thelatch point 29 of the arm 30, which is secured to the rock shaft 31bymeans of a pin 30-A which journals in the gear case front 32 and hasattached on the outer end thereof by means of a shear pin 33 a lever 34whose handle 35 is normally urged in an upward direction by the spring'70 36. The spring 36 is placed on the rod 3'7 whose lower end isattached to the lever 34 and whose lower end passes through the lug 38which forms a support for the spring 36. The upper end 39 is threaded toreceive the nuts 40 by means of which the compression of the spring 36may be varied. I

The angle of the side of the notches 28 and the compression of thespring 36 are so proportioned as to provide for the handling of ordisonary loads on the worm 11, but should this load become excessive thecage 22 will become unlatched permitting the gear 15 to disengage theparticular pinion with which it may be in mesh, and the rotation of thecage 22 is stopped by 35 the latch point 29 dropping into the next notch27, thereby holding the gear set in a neutral position from which itcannot be changed until the handle 35 is depressed and the cage 22rotated by means of the dial 41.

It is desirable that the pin 33 shall be more easily sheared than thepin 30-A in order that if too much compression is placed on the spring36, or the lever 34 is prevented from movement by a plug between sameand the floor, or in any other manner that an excessive load will shearthe pin 33, which is on the outside of the gear case and thereforereadily accessible.

Referring now to Fig. 5 it will be seen that the lever 34'-A is providedwith a notch 42 which engages the lug 43 of a forked rocker arm 44arranged to operate a toggle switch 45 in the circuit 46, which may bemade to include any or all of three electrically operated devices,namely an alarm bell 4'7, a lamp 48 or an electrically oper- 05 atedswitch 49 for opening the motorcircuit 50.

In this form of the device whenever the lever 34-A drops by reason of anoverload having caused the latch point 29 to be withdrawn from itsrespective notch 28, the rocker arm 44 will actuate the switch 45 andannounce the fact, either audibly or visibly, that the coal feed hasstopped, and at the same time will stop the operation of the motorthereby preventing its unnecessary operation, and at the same time, andmore important, preventing the operation of the fan which wouldotherwise cause all of the fuel in the retort to be burned, to thedetriment of the tuyere elements themselves. I

In Figs. 6 to 8 inclusive the cage 51 is prevented from being driven bya latch arm 52 provided with a hardened face 53 which engages theshoulders 54 disposed about the periphery of the cage 51. The arm 52 issupported by a stub shaft 55 which journals in the hub 56 of the gearcase front 57. The hub 56 is provided with a slot 58' which receives thepin 59. The pin 59 passes through the shaft 55 and holds it in placewithin the hub 56. The slot 58 permits a limited rocking movement of theshaft 55. The shaft 55 is provided with a square end 60 for theapplication of a key or wrench for manually unlatching the cage 51. Thearm 52 is urged toward the cage 51 by means of a compression spring 61within the housing 62. The compression of the spring 61-may be varied bythe set of the screw 63 and maintained by the lock nut 64.

In this form of the device the unloading mechanism is all containedwithin the gear case itself and is not as susceptible to tampering as isthe first described form of the device, although the two modificationsdescribed herein are identical in principle.

The operation of the deviceshown in Figs. 6 to 8 is identical with thatshown in Figs. 1 to 5 inclusive, it being understood that the signalingand cut-out devices are applicable to either form. and that in eithercase when an overload has permitted the gears to move to a neutralposition they must be returned to a driving position after thedifliculty which occasioned the unloading has been removed before thecoal-feeding operation can be resumed.

I am aware that many forms of unloading devices have been constructed inthe past; it is therefore not my intention to cover such devicesbroadly, but I do intend to cover all such forms and modificationsthereof as fall fairly within the appended claims.

I claim:

1. A mechanical unloader for underfeed stokers having in combination arotatable selective gear set with a latch means for holding one set ofgears in an operative position, and unloading means for releasing saidgear set at the moment of overload and permitting same to pass'to aneutral position.

2. A mechanical unloader for underfeed stokers the combination of arotatable gear case, and a spring-urged latch adapted to hold the cagein a driving position under a given load and to release same to aneutral position when said load is exceeded.

3. An unloading mechanism for selective rotatable gear sets consistingof a latch for holding said set in an operative position, manual. meansfor disengaging said latch, a frangible pinbetween said manual means andsaid latch, and an.

adjustable spring means for urging said latch toward a holding position.

HASKELL C. CARTER.

